1. Field of the Invention
The present invention relates generally to an improved testing system and in particular to a computer implemented method, testing system, computer usable program code, and apparatus to measure microprocessor susceptibility. More specifically, the present invention relates to a computer implemented method, testing system, computer usable program code, and apparatus for measuring microprocessor susceptibility to internal noise generation by running targeted components while modulating adjacent components.
2. Description of the Related Art
With the ever-increasing computer system operation frequency and power dissipation of complimentary metal oxide semiconductor (CMOS) chips, variations of the on-chip switching activity can cause large variations of the current demand of a multi-processor multi-chip module (MCM). The current variations can amount to more than 100 amps within a few nanoseconds for an IBM high-performance system. The resulting mid-frequency voltage variations on the power and ground distribution system must be contained within specified noise margins with an appropriate low impedance power distribution system and decoupling capacitors on the multi-chip module and the system board to ensure system functionality. On-chip decoupling capacitors are required for high frequency power noise containment and they additionally help to reduce mid-frequency noise.
As a microprocessor draws more current and operates on lower voltage, providing a clean path to chip power distribution becomes very important. In providing a clean path to chip power distribution, decoupling capacitors have been used to provide a microprocessor with a stable voltage at different level, such as chip, substrate, and card. Traditionally, decoupling capacitors have been selected such that they protect all of the frequency ranges of interest. An impedance target, which is flat from DC to high frequency, has been used to meet the allowable noise ripples in voltage. Current solutions are conservative and expensive because they require numerous decoupling capacitors that work in different narrow frequency bands. As cost rises as one of the dominant factors in designing computer systems, defining detailed decoupling requirements are becoming more important. Defining detailed decoupling requirements makes developing a method for optimized, cost-effective decoupling solutions more critical.